Gas turbine engines are operated over a wide range of operating conditions and are required to handle various flow conditions during operation. The fluid-structure-acoustic interactions that occur in fluid systems of such engines can exhibit resonances or pressure fluctuations resulting in undesirable consequences, such as noise generation, vibratory stresses, etc. The amplitude and frequency of the excitation or the undesirable noise vary with a number of parameters, including the operating and/or flow conditions, and configuration of the related components of the fluid systems.
Resonators have been used to mitigate the noise and associated stress on the affected components. A conventional single resonator design is tuned to a specific target frequency, and therefore it is effective but only over a narrow range of frequencies. However, the target frequency of the generate noise can sometimes change quite significantly with engine power or varied operating and/or flow conditions. Hence, in an effort to attenuate or dump pressure fluctuations or acoustic waves over a range of frequencies, several customized resonators can sometimes be required to cover those frequencies, thereby adding undesirable cost and weight to the engine.